Drainage Contractor November 2017 : Page 30

Excavator Mounted 22” Models now available ENVIRONMENT Start your new service today • Multi purpose attachment • Creates a 2 stage ditch • Environmentally friendly • Self levels spoil • Direct Drive • Reach and precision of an excavator www.ditchdoctor.ca 902-662-2234 Check out videos on website In conducting research on saturated buffers, several monitor-ing wells are installed (front) between the underground distribution pipe (as indicated by the control box in the background here) and the water leaving the buffer (left). Photo courtesy of Kent Heikens, USDA-ARS. that lack the additional space. “We’re going to intercept the tile outlet within the buffer, put in a control box, and then use that to raise the water table within that outlet,” he explains. “Then we put in a new distribution pipe, just some perforated tile, which runs along the field edge of the buffer.” The new distribution pipe is installed fairly shallow he says, preferably two-and-a-half feet below the ground surface, and this is what enables the water control box intercepting the tile flow to raise the water table up into the new distribution pipe so that pipe stays full and water leaks out into the buffer for maximum nitrate removal. “If we have about a meter of relief, we can raise that water table in the buffer and we don’t impact the farmer’s drainage system at all,” he says, “and that’s what’s ideal, because once we put this in, the farmer doesn’t have to do anything, just go out once a year and make sure that no junk has filled the box. I think it is a real benefit for this practice.” Jaynes says that the practice is most suited to soils with a lot of carbon in them, because it’s the carbon that is stimulating denitrification of the water while it seeps through the saturated buffer. Locations where the soil is very dark near waterways, (which is very typical in Iowa or Minnesota) needs to test positive for more than one percent carbon, as deep as three-or-four feet into the soil profile. He also explains that it’s helpful when the buffer is lower than the field landscape, otherwise the rest of the tile drainage system will be impeded by artificially raising the water table with the control box. The last thing to consider is how far the new distribution tile can be run through the buffer. “The longer you can extend that, the more nitrate you can remove,” he says. “And, typically, we run up against a property line we can’t go across.” Jaynes says that in cases like this, start at zero grade and get shallower as you go downstream, or deeper as you go upstream. “Just don’t go any deeper than four feet or more 30 DRAINAGE CONTRACTOR | NOVEMBER 2017 DC_Agridrain_May16_CSA.indd 1 2016-04-21 12:26 PM